Imaging apparatus

ABSTRACT

An imaging apparatus includes a first member including a holding member, the retaining member holding a lens; a second member surrounding the first member; an imaging device arranged opposite to the first member and the lens; and a driving member arranged in a region adjacent to the first member driving the first member in the vertical direction relative to the imaging device. The first member includes at least a first portion and a second portion, the first portion having a first outer diameter and the second portion having a second outer diameter smaller than the first outer diameter, the first and second portions respectively having a first corner and a second corner, the first and second corners respectively having a first cutout portion and a second cutout portion. At least a portion of the driving member is disposed at a region corresponding to the second portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of application Ser. No.14/157,036, filed Jan. 16, 2014, which is a Continuation of applicationSer. No. 12/814,973, filed on Jun. 14, 2010, now Abandoned, and claimspriority to Japanese Patent Application JP 2009-163284 filed in theJapanese Patent Office on Jul. 10, 2009, the entire contents of whichare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging apparatus, and particularlyto an imaging apparatus that allows reduction in size of a lens drivingportion.

2. Description of the Related Art

FIG. 1 shows the configuration of an exemplary imaging apparatus ofrelated art. An imaging apparatus 10 shown in FIG. 1 includes a housing11, a lens barrel 12, and an imaging device 13. The imaging apparatus 10is manufactured by assembling the lens barrel 12 and the imaging device13 into the housing 11.

Lenses 21, 22, and 23 are assembled into the lens barrel 12 and heldtherein. A thread 24 is provided on the outer side surface of the lensbarrel 12. The thread 24 engages a thread (not shown) provided on a lenscarrier 31 disposed in the housing 11. The thread engagement between thelens barrel 12 and the lens carrier 31 allows the distance to theimaging device 13 to be adjusted at the time of manufacture (the focusof the lenses to be adjusted). After the focus adjustment, the lensbarrel 12 is glued to the lens carrier 31 so that the lens barrel 12 isfixed to the lens carrier 31.

Coils 32-1 and 32-2 are provided on the side surface of the lens carrier31. The coils 32-1 and 32-2 are shown as separate members forillustration purposes only, but a single coil 32 is in practice providedon the side surface of the lens carrier 31. A magnet 33-1 is provided inthe housing 11 and faces the coil 32-1. Similarly, a magnet 33-2 isprovided in the housing 11 and faces the coil 32-2. Each of the magnets33-1 and 33-2 is provided with a yoke, which is omitted in FIG. 1. Thecoil 32, the magnets 33, and the yokes form a voice coil motor.

When a current is conducted through the coil 32, a force is produced inthe upward or downward direction in FIG. 1. The produced force moves thelens carrier 31 in the upward or downward direction. When the lenscarrier 31 is moved, the lens barrel 12 fixed to the lens carrier 31 isalso moved. The distance between the lenses 21 to 23 held in the lensbarrel 12 and the imaging device 13 therefore changes. The mechanismdescribed above enables autofocusing (AF) (see JP-A-2007-17791, forexample).

SUMMARY OF THE INVENTION

It is desirable in recent years to reduce the size of an AF driver asthe size of digital cameras has been reduced and mobile phones having adigital camera capability have become popular. The size of an AF drivercan be reduced by reducing the size of an optical system, such aslenses, but in return the amount of light likely decreases,disadvantageously resulting in degradation in image quality. It istherefore not preferable to reduce the size of lenses or similar opticalcomponents in order to reduce the size of an AF driver. Nevertheless,further reduction in size of the driver (an imaging apparatus includingthe driver) is desired, as described above.

It is difficult to achieve further size reduction unless a change ismade to the configuration shown in FIG. 1. The size of the imagingapparatus can be reduced by reducing the sizes of the lenses 21 to 23 toreduce the size of the lens barrel 12 with no change made to theconfiguration shown in FIG. 1. In this case, however, it is difficult toavoid the degradation in image quality described above.

JP-A-2007-17791 describes an imaging apparatus that has a sectordisposed between a subject and a lens and blocking light incident to thelens and how to reduce the size of the imaging apparatus. The imagingapparatus described in JP-A-2007-17791 includes a lens group containinga plurality of lenses having different diameters, and the sector isdisposed between a subject and the lens group and blocks light incidentto the lens group. The lens group is accommodated in a lens barrel. Theouter circumferential sidewall of the lens barrel has a plurality ofstepped sections having different diameters corresponding to thediameters of the lenses accommodated in the lens barrel, and a sidewallrecess is formed along one of the stepped sections. Sector drive meansfor driving the sector is disposed in the sidewall recess.

The imaging apparatus described in JP-A-2007-17791 is desired to befurther reduced in size. The imaging apparatus described inJP-A-2007-17791 has a disadvantageous structure in which, for example,the lens barrel has no thread mechanism, which does not allow focusadjustment between the lens group and the imaging device at the time ofmanufacture.

Lens driving methods have also been proposed without using the drivingmethod described with reference to FIG. 1. For example, a driving methodusing a piezoelectric device and a driving method using a shape memoryalloy have been proposed. It is desirable that the other driving methodsdescribed above can also be used and the size of a drive-related portioncan be reduced.

Thus, it is desirable to reduce a lens driving portion.

An imaging apparatus according to an embodiment of the inventionincludes a first member that holds a lens, a second member to which thefirst member is fixed, and drive means for driving the second member inthe vertical direction relative to an imaging plane of an imagingdevice. The first member has diameters different from each other, and aportion having a small diameter has a portion that engages the secondmember. The drive means is disposed in a space created by the differencebetween the different diameters.

The first member may hold a plurality of lenses having diametersdifferent from one another and may be shaped to have diameterscorresponding to the diameters of the lenses.

The drive means may be a voice coil motor formed of a coil, a magnet,and a yoke. The voice coil motor may be disposed in the space describedabove. The coil of the voice coil motor may be disposed on the sidesurface of the second member.

The drive means may include a piezoelectric device, a shaft connected tothe piezoelectric device, and a hook which is connected to the secondmember and through which the shaft passes. The piezoelectric device, theshaft, and the hook may be disposed in the space described above.

The drive means may include a wire made of a shape memory alloy, a hookto which the wire is hooked, and electrodes connected to the wire. Thewire, the hook, and the electrodes may be disposed in the spacedescribed above.

In an imaging apparatus according to another embodiment of theinvention, a thread is provided on a portion of a member that holdslenses, specifically, on the portion whose diameter corresponds to thelens having the smallest diameter, and the thread allows the portion toengage a member that drives the lenses. Drive means is provided in thespace created by the different diameters.

According to the embodiments of the invention, the size of a lensdriving portion can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration of an exemplary imaging apparatus ofrelated art;

FIG. 2 shows the configuration of an imaging apparatus of an embodimentto which the invention is applied;

FIG. 3 describes the configuration of the imaging apparatus;

FIG. 4 describes the size of the imaging apparatus;

FIGS. 5A and 5B show the configuration of an exemplary imaging apparatusof related art for comparison;

FIGS. 6A and 6B show the configuration of the imaging apparatus ofanother embodiment to which the invention is applied;

FIGS. 7A and 7B show the configuration of an exemplary imaging apparatusof related art for comparison;

FIGS. 8A and 8B show the configuration of the imaging apparatus ofanother embodiment to which the invention is applied; and

FIG. 9 shows the configuration of the imaging apparatus of anotherembodiment to which the invention is applied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will be described below with reference tothe drawings.

The invention can be applied to an imaging apparatus. The imagingapparatus described herein is specifically an apparatus accommodated in,for example, a digital still camera and a mobile phone having a digitalstill camera capability. In such an imaging apparatus, autofocusing (AF)is performed by driving a lens (for example, moving a lens relative toan imaging device in such a way that the lens approaches the imagingdevice or travels away therefrom).

An imaging apparatus including a driver for performing autofocusing hasa configuration, for example, shown in FIG. 1. Referring to FIG. 1again, the imaging apparatus 10 is formed of the housing 11, whichaccommodates the lens carrier 31. The lens carrier 31 is configured tobe movable relative to the housing 11 in the upward and downwarddirections in FIG. 1 (approaching the imaging device 13 or travelingaway therefrom). The lens barrel 12, which accommodates the plurality oflenses 21 to 23, is disposed in the lens carrier 31 and fixed thereto.

The embodiments described below primarily relate to the lens barrel andthe lens carrier of the imaging apparatus described above. An imagingapparatus using a lens barrel and a lens carrier to which any of theembodiments described below is applied can be smaller than an imagingapparatus of related art. When such a smaller imaging apparatus isaccommodated in an apparatus, such as a digital still camera and amobile phone, the size of the apparatus can be reduced. Further, thespace for the portion other than the imaging apparatus can be increased,whereby other functions can be enhanced.

A description will next be made of an imaging apparatus expected to showthe advantageous effects described above. Methods for performingautofocusing having been proposed include a method using a voice coilmotor (the method described with reference to FIG. 1), a method using apiezoelectric device, and a method using a wire made of a shape memoryalloy. In the following description, the embodiments will be describedwith reference to the methods described above. That is, the followingdescription includes a first embodiment in which a voice coil motor isused to perform autofocusing, a second embodiment in which apiezoelectric device is used to perform autofocusing, and a thirdembodiment in which a wire made of a shape memory alloy is used toperform autofocusing.

In the following description, a member that holds a lens is referred toas a lens barrel, a member to which the lens barrel is fixed is referredto as a lens carrier, and a portion that drives the lens carrier isreferred to as a driver, as appropriate. The lens barrel is a cylindershaped in such a way that an upper diameter (outer diameter) and a lowerdiameter (outer diameter) are designed to match the respective lensdiameters and hence different from each other. A portion (thread) thatengages the lens carrier is provided on one of the upper and lowerportions of the lens barrel, the portion having a smaller diameter. Thedifference in diameter creates a space, and drive means is provided inthe created space. The drive means in the first to third embodimentdiffer from one another as described above and will be described below.

First Embodiment

A first embodiment will be described below. FIG. 2 shows an exemplaryconfiguration of an imaging apparatus 100 in the first embodiment and isa cross-sectional view of the imaging apparatus 100. The imagingapparatus 100 shown in FIG. 2 includes a housing 101, a lens barrel 102,and an imaging device 103. FIG. 3 is an exploded view of respectiveparts of the imaging apparatus 100 shown in FIG. 2.

Referring to FIG. 3, lenses 21, 22, and 23 are assembled into the lensbarrel 102 and held therein. A thread 111 is provided on the outer sidesurface of the lens barrel 102.

A lens carrier 121 is provided in the housing 101. A thread 122 isprovided on the inner side (inner diameter) of the lens carrier 121. Acoil 123 is provided on the outer (outer shape) side surface of the lenscarrier 121. The coil 123 surrounds the side surface of the lens carrier121. Magnets 124-1 and 124-2 are provided in predetermined positions onthe inner side (inner diameter) of the housing 101 and face the coil123. The magnets 124-1 and 124-2 are disposed on opposite sides of thecoil 123.

Each of the magnets 124-1 and 124-2 is provided with a yoke, but shownas a combined magnet and yoke in FIGS. 2 and 3 as magnet 124-1 or magnet124-2. When it is not necessary to distinguish the magnets 124-1 and124-2 from each other, the magnets 124-1 and 124-2 are hereinaftersimply referred to as magnets 124.

The thread 111 on the lens barrel 102 engages the thread 122 provided onthe lens carrier 121. The engagement between the lens barrel 102 and thelens carrier 121 allows the distance to the imaging device 103 to beadjusted at the time of manufacture (the focus of the lenses to beadjusted). After the focus adjustment, the lens barrel 102 is glued tothe lens carrier 121 so that the lens barrel 102 is fixed to the lenscarrier 121.

After the lens barrel 102 is inserted into the housing 101 and fixed tothe lens carrier 121, the imaging device 103 is inserted into thehousing 101 and fixed thereto. The imaging apparatus 100 having theconfiguration shown in FIG. 2 is manufactured by sequentially assemblingthe lens barrel 102 and the imaging device 103 into the housing 101 asdescribed above.

In the imaging apparatus 100 having the configuration described above,when a current is conducted through the coil 123 provided on the lenscarrier 121, the interaction between the current and the magnets 124produces a force oriented in the upward or downward direction in FIGS. 2and 3 depending on the direction in which the current flows. Theproduced force moves the lens carrier 121 in the upward or downwarddirection. When the lens carrier 121 is moved, the lens barrel 102 fixedto the lens carrier 121 is also moved. The distance between the lenses21 to 23 held in the lens barrel 102 and the imaging device 103therefore changes. Autofocusing (AF) is performed by the mechanismdescribed above.

The structure of the lens barrel 102 will further be described.Referring to FIG. 3, the lens barrel 102 has a stepped shape, a shapehaving two stepped sections in the configuration shown in FIG. 3. Astepped section 151 contains the lens 23, and a stepped section 152contains the lenses 21 and 22. As shown in FIG. 3, the sizes of thelenses 21 to 23 satisfy the following relationship.lens 21<lens 22<lens 23

The diameter of the stepped section 151 containing the lens 23 istherefore larger than that of the stepped section 152 containing thelenses 21 and 22. The diameter of the stepped section 151 is slightlylarger than that of the lens 23. The diameter of the stepped section 152is slightly larger than that of the lens 22 but smaller than that of thelens 23.

The thread 111 is provided on the stepped section 152. The thread 111provided on the stepped section 152 engages the thread 122 provided onthe lens carrier 121. The diameter of the lens carrier 121 is sized insuch a way that the thread ill engages the thread 122. The diameter ofthe lens carrier 121 is therefore sized to be slightly larger than thatof the stepped section 152.

Further, the height of the stepped section 152 is shorter than that ofthe lens carrier 121. The height used herein means the length in theup-down direction in FIG. 3 (the direction toward or away from theimaging device). The height of the lens carrier 121 is determined insuch a way that the stepped section 151 of the lens barrel 102 does notcome into contact with an end of the lens carrier 121 when the lensbarrel 102 is fixed to the lens carrier 121.

The imaging apparatus 10 of related art is now compared with the imagingapparatus 100 in the first embodiment. The upper portion of FIG. 4 showsthe configuration of the imaging apparatus 10 of related art shown inFIG. 1, and the lower portion of FIG. 4 shows the configuration of theimaging apparatus 100 in the first embodiment of the invention shown inFIG. 2.

Each of the imaging apparatus 10 and the imaging apparatus 100 includesthe lenses 21 to 23. The imaging apparatus 10 and the imaging apparatus100 therefore do not differ from each other in terms of optical systemand can hence capture images having the same image quality. Further, theimaging device 13 in the imaging apparatus 10 and the imaging device 103in the imaging apparatus 100 have the same number of pixels and cancapture images having the same image quality in this regard as well.

It is, however, obvious that the imaging apparatus 100 is smaller thanthe imaging apparatus 10. The reason for this is that the lens barrel102 in the imaging apparatus 100 has a stepped shape and the diameter ofthe stepped section 152 accommodating the smaller lenses is smaller thanthe diameter of the stepped section 151 accommodating the larger lens.The size of the imaging apparatus 100 can be reduced accordingly. Thesize of the imaging apparatus 100 is reduced because the space createdby the difference between the stepped sections 151 and 152,specifically, the difference in diameter between the stepped sections151 and 152, accommodates the lens carrier 121, the thread 122, the coil123, and the magnets 124.

That is, the size of the imaging apparatus 100 can be reduced by shapingthe lens barrel 102 in such a way that the diameter thereof graduallydecreases in correspondence with the sizes of the lenses to beaccommodated, providing the thread 111 on the stepped section having thesmaller diameter so that the threaded portion engages the lens carrier121, and assembling a driver including the coil 123 and the magnets 124on the side where the diameter is smaller.

In the above description of “shaping the lens barrel 102 in such a waythat the diameter thereof gradually decreases in correspondence with thesizes of the lenses to be accommodated,” “the diameter thereof graduallydecreases” means that the following shapes can be employed. That is, forexample, a stepped shape, like the stepped sections 151 and 152 shown inFIG. 3, can be employed. Although not shown, when three lenses, such asthe lenses 21 to 23 shown in FIG. 3, are incorporated, a stepped shapenot formed of two stepped sections but formed of three stepped sectionscorresponding to the number of lenses can be employed.

Alternatively, although not shown, instead of a stepped shape, forexample, a cone shape (part of a cone shape) whose diameter graduallyand continuously decreases in the direction away from the imaging device103 can be employed. Still alternatively, for example, a combined shapein which the threaded portion (corresponding to the stepped section 152in FIG. 3) has a cylindrical shape and the non-threaded portion(corresponding to the stepped section 151 in FIG. 3) has part of a coneshape can be employed. Still alternatively, any shape one can think offrom the shapes described above can be employed.

In the imaging apparatus 10 of related art shown in the upper portion ofFIG. 4, the lens carrier 31 is positioned outside the lens barrel 12,and the coil 32 and the magnets 33 are further positioned outside thelens carrier 31. That is, when the configuration described above isemployed, the diameter of the lens carrier 31 is greater than that ofthe lens barrel 12, and the coil 32 and the magnets 33 are furtherpositioned outside the large-diameter lens carrier 31, disadvantageouslyresulting in an increased size of the imaging apparatus 10 itself.

On the other hand, since the imaging apparatus 100 shown in the lowerportion of FIG. 4, to which the first embodiment of the invention isapplied, has the configuration described above, the lens carrier 121 ispositioned outside the lens barrel 102 but inside the largest-diameterportion (outer diameter) of the lens barrel 102. Further, the coil 123and the magnets 124 positioned outside the lens carrier 121 arepositioned inside the outer diameter of the lens barrel 102. Since noneor only part of the lens carrier 121, the coil 123, and the magnets 124is thus positioned outside the outer diameter of the lens barrel 102,the size of the imaging apparatus 100 itself is reduced.

In other words, the diameter of the lens barrel 102 on the side wherethe imaging device 103 is present is large, whereas the diameter of thelens barrel 102 on the opposite side is small. Since the diameters ofthe two portions of the lens barrel 102 differ from each other, a spaceis created where the difference is present. Accommodating drive means(the coil 123, the magnets 124, and the yokes in this case) forvertically moving the lens carrier 121 relative to the imaging plane ofthe imaging device 103 in the space allows the size of the imagingapparatus 100 to be reduced.

As described above, the size of the imaging apparatus can be reduced byapplying the invention. Further, the size reduction will not degrade thequality of a captured image.

The focus adjustment carried out at the time of manufacture by using theengagement between the lens barrel 102 and the lens carrier 121 can becarried out in the same manner as the imaging apparatus 10 of relatedart.

Second Embodiment

A second embodiment will be described below. The second embodimentrelates to a case where a piezoelectric device is used to performautofocusing. A piezoelectric device is a passive device using apiezoelectric effect in which a force applied to a piezoelectric memberis converted into a voltage and vice versa. To describe an imagingapparatus using a piezoelectric device to perform autofocusing, theconfiguration of an imaging apparatus of related art is first shown inFIGS. 5A and 5B for comparison. FIG. 5A is a top view of an imagingapparatus 200, and FIG. 5B is a side view (cross-sectional view) of theimaging apparatus 200.

The imaging apparatus 200 includes a housing 201, a lens barrel 202, andan imaging device 203. Lenses 21, 22, and 23 are assembled into the lensbarrel 202 and held therein. A thread 211 is provided on the outer sidesurface of the lens barrel 202.

A lens carrier 221 is provided in the housing 201. A thread 222 isprovided on the inner side (inner diameter) of the lens carrier 221. Aslide hook 223 is provided in a predetermined position on the outer(outer shape) side surface of the lens carrier 221. One of the ends ofthe slide hook 223 is connected to the lens carrier 221, and the otherend has a circular shape having a circular hole at the center thereof. Ashaft 224 passes through the hole.

A piezoelectric device 225 fixed to the housing 201 is attached to theshaft 224. When a current is conducted through the piezoelectric device225, a force is produced and then the slide hook 223 slides. When theslide hook 223 slides, the lens carrier 221 moves relative to thehousing 201 in the upward or downward direction (the direction toward oraway from the imaging device 203). Autofocusing is thus performed.

In the imaging apparatus 200 of related art shown in FIGS. 5A and 5B,the lens carrier 221 is positioned outside the lens barrel 202 and theslide hook 223, the shaft 224, and the piezoelectric device 225 arefurther positioned outside the lens carrier 221. That is, when theconfiguration described above is employed, the diameter of the lenscarrier 221 is greater than that of the lens barrel 202, and the slidehook 223, the shaft 224, and the piezoelectric device 225 are furtherpositioned outside the large-diameter lens carrier 221, resulting in anincreased size of the imaging apparatus 200 itself.

To address the problem, the imaging apparatus in the second embodimentto which the invention is applied has the configuration shown in FIGS.6A and 6B to reduce the size of the imaging apparatus. FIG. 6A is a topview of an imaging apparatus 250, and FIG. 6B is a side view(cross-sectional view) of the imaging apparatus 250.

The imaging apparatus 250 shown in FIGS. 6A and 6B has a configurationthat is basically the same as that of the imaging apparatus 200 ofrelated art shown in FIGS. 5A and 5B. The imaging apparatus 250 includesa housing 251, a lens barrel 252, and an imaging device 253. Lenses 21,22, and 23 are assembled into the lens barrel 252 and held therein. Athread 261 is provided on the outer side surface of the lens barrel 252.

A lens carrier 271 is provided in the housing 251. A thread 272 isprovided on the inner side (inner diameter) of the lens carrier 271. Aslide hook 273 is provided in a predetermined position on the outer(outer shape) side surface of the lens carrier 271. One of the ends ofthe slide hook 273 is connected to (integrated with) the lens carrier271, and the other end has a circular shape having a circular hole atthe center thereof. A shaft 274 passes through the hole.

A piezoelectric device 275 fixed to the housing 251 is attached to theshaft 274. When a current is conducted through the piezoelectric device275, a force is produced and then the slide hook 273 slides. When theslide hook 273 slides, the lens carrier 271 moves relative to thehousing 251 in the upward or downward direction (the direction toward oraway from the imaging device 253). Autofocusing is thus performed.

The structure of the lens barrel 252 will further be described.Referring to FIG. 6B, the lens barrel 252 has a stepped shape, a shapehaving two stepped sections in the configuration shown in FIG. 6B. Astepped section 281 contains the lens 23, and a stepped section 282contains the lenses 21 and 22. As shown in FIG. 6B, the sizes of thelenses 21 to 23 satisfy the following relationship.lens 21<lens 22<lens 23

The diameter of the stepped section 281 containing the lens 23 istherefore larger than that of the stepped section 282 containing thelenses 21 and 22. The diameter of the stepped section 281 is slightlylarger than that of the lens 23. The diameter of the stepped section 282is slightly larger than that of the lens 22 but smaller than that of thelens 23.

The thread 261 is provided on the stepped section 282. The thread 261provided on the stepped section 282 engages the thread 272 provided onthe lens carrier 271. The diameter of the lens carrier 271 is sized insuch a way that the thread 261 engages the thread 272. The diameter ofthe lens carrier 271 is therefore sized to be slightly larger than thatof the stepped section 282.

Further, the height of the stepped section 282 is shorter than theheight of the lens carrier 271. The height used herein means the lengthin the up-down direction in FIG. 6B (the direction toward or away fromthe imaging device 253). The height of the lens carrier 271 isdetermined in such a way that the stepped section 281 of the lens barrel252 does not come into contact with an end of the lens carrier 271 whenthe lens barrel 252 is fixed to the lens carrier 271.

The imaging apparatus 200 of related art is now compared with theimaging apparatus 250 in the second embodiment. Each of the imagingapparatus 200 and the imaging apparatus 250 includes the lenses 21 to23. The imaging apparatus 200 and the imaging apparatus 250 therefore donot differ from each other in terms of optical system and can hencecapture images having the same image quality. Further, the imagingdevice 203 in the imaging apparatus 200 and the imaging device 253 inthe imaging apparatus 250 have the same number of pixels and can captureimages having the same image quality in this regard as well.

It is, however, obvious that the imaging apparatus 250 is smaller thanthe imaging apparatus 200. The reason for this is that the lens barrel252 in the imaging apparatus 250 has a stepped shape and the diameter ofthe stepped section 282 accommodating the smaller lenses is smaller thediameter of the stepped section 281 accommodating the larger lens. Thesize of the imaging apparatus 250 can be reduced accordingly. The sizeof the imaging apparatus 250 is reduced because the space created by thedifference between the stepped sections 281 and 282, specifically, thedifference in diameter between the stepped sections 281 and 282,accommodates all or part of the lens carrier 271, the slide hook 273,and the shaft 274.

That is, the size of the imaging apparatus 250 can be reduced by shapingthe lens barrel 252 in such a way that the diameter thereof graduallydecreases in correspondence with the sizes of the lenses to beaccommodated, providing the thread 261 on the stepped section having thesmaller diameter so that the threaded portion engages the lens carrier271, and assembling a driver including the slide hook 273, the shaft274, and the piezoelectric device 275 on the side where the diameter issmaller.

In the above description of “shaping the lens barrel 252 in such a waythat the diameter thereof gradually decreases in correspondence with thesizes of the lenses to be accommodated,” “the diameter thereof graduallydecreases” means that the following shapes can be employed. That is, forexample, a stepped shape, like the stepped sections 281 and 282 shown inFIG. 6B, can be employed. Although not shown, when three lenses, such asthe lenses 21 to 23 shown in FIG. 6B, are incorporated, a stepped shapenot formed of two stepped sections but formed of three stepped sectionscorresponding to the number of lenses can be employed.

Alternatively, although not shown, instead of a stepped shape, forexample, a cone shape (part of a cone shape) whose diameter graduallyand continuously decreases in the direction away from the imaging device253 can be employed. Still alternatively, for example, a combined shapein which the threaded portion (corresponding to the stepped section 282in FIG. 6B) has a cylindrical shape and the non-threaded portion(corresponding to the stepped section 281 in FIG. 6B) has part of a coneshape can be employed. Still alternatively, any shape one can think offrom the shapes described above can be employed.

The imaging apparatus 200 of related art shown in FIGS. 5A and 5Bdisadvantageously has a structure that causes an increase in size of theimaging apparatus 200 itself, as described above. However, since theimaging apparatus 250 shown in FIGS. 6A and 6B, to which the secondembodiment of the invention is applied, has the configuration describedabove, the lens carrier 271 is positioned outside the lens barrel 252but inside the largest-diameter portion of the lens barrel 252.

Further, all or part of the driver including the slide hook 273, theshaft 274, and the piezoelectric device 275 positioned outside the lenscarrier 271 is positioned inside the largest-diameter portion (largestouter diameter) of the lens barrel 252. Since none or only part of thelens carrier 271, the slide hook 273, the shaft 274, and thepiezoelectric device 275 is thus positioned outside the largest outerdiameter of the lens barrel 252, the size of the imaging apparatus 250itself is reduced.

In other words, the diameter of the lens barrel 252 on the side wherethe imaging device 253 is present is large, whereas the diameter of thelens barrel 252 on the opposite side is small. Since the diameters ofthe two portions of the lens barrel 252 differ from each other, a spaceis created where the difference is present. Accommodating drive means(the slide hook 273, the shaft 274, and the piezoelectric device 275 inthis case) for vertically moving the lens carrier 271 relative to theimaging plane of the imaging device 253 in the space allows the size ofthe imaging apparatus 250 to be reduced.

As described above, the size of the imaging apparatus can be reduced byapplying the invention.

The focus adjustment carried out at the time of manufacture by using theengagement between the lens barrel 252 and the lens carrier 271 can becarried out in the same manner as the imaging apparatus 200 of relatedart.

The imaging apparatus 250 shown in FIGS. 6A and 6B includes one set ofthe slide hook 273 and the shaft 274, two to four sets of a slide hookand a shaft can be provided. The sets of a slide hook and a shaft otherthan the set of the slide hook 273 and the shaft 274 are provided tosupport the lens carrier 271 but provided with no piezoelectric device.Providing a plurality of sets of a slide hook and a shaft in the imagingapparatus 250 does not increase the size of the configuration of theimaging apparatus 250, but the imaging apparatus 250 can still bereduced in size.

Third Embodiment

A third embodiment will be described below. The third embodiment relatesto a case where a wire made of a shape memory alloy is used to performautofocusing. A shape memory alloy is characterized in that the lengththereof increases or decreases when a current is conducted therethrough.To describe an imaging apparatus using a wire made of a shape memoryalloy to perform autofocusing, the configuration of an imaging apparatusof related art is first shown in FIGS. 7A and 7B for comparison. FIG. 7Ais a top view of an imaging apparatus 300, and FIG. 7B is a side view(cross-sectional view) of the imaging apparatus 300.

The imaging apparatus 300 includes a housing 301, a lens barrel 302, andan imaging device 303. Lenses 21, 22, and 23 are assembled into the lensbarrel 302 and held therein. A thread 311 is provided on the outer sidesurface of the lens barrel 302.

A lens carrier 321 is provided in the housing 301. A thread 322 isprovided on the inner side (inner diameter) of the lens carrier 321.Hooks 323-1 and 323-2 are provided in predetermined positions on theouter (outer shape) side surface of the lens carrier 321. The hooks323-1 and 323-2 are disposed on opposite sides of the lens carrier 321.A wire 332 made of a shape memory alloy is hooked to the hooks 323-1 and323-2 (hereinafter simply referred to as the hooks 323 when they are notnecessary to be distinguished and the same applies to other portions inthe following description).

The wire 332 is also connected to electrodes 331-1 and 331-2. When acurrent is conducted from the electrodes 331-1 and 331-2 through thewire 332 and the temperature thereof increases, the wire 332 made of ashape memory alloy decreases in length. When the length of the wire 332decreases, the hooks 323 to which the wire 332 is hooked are liftedrelative to the housing 301.

Since the hooks 323 are integrated with the lens carrier 321, the hooks323 lifted relative to the housing 301 lift the lens carrier 321relative to the housing 301. In this way, the lens carrier 321 isdriven. Conversely, when the current flowing through the wire 332 isterminated, the temperature thereof decreases and the length thereofincreases. When the length of the wire 332 increases (returns back toits original length), the hooks 323 and hence the lens carrier 321 arelowered.

The lens barrel 302, which holds the lenses, fits into the lens carrier321. Driving the lens carrier 321 in the way described above thereforechanges the position of the lenses held in the lens barrel 302 and hencethe focal distance is adjusted. That is, autofocusing is performed.

In the imaging apparatus 300 of related art shown in FIGS. 7A and 7B,the lens carrier 321 is positioned outside the lens barrel 302, and thehooks 323, the wire 332, and the electrodes 331 are further positionedoutside the lens carrier 321. That is, when the configuration describedabove is employed, the diameter of the lens carrier 321 is greater thanthat of the lens barrel 302, and the hooks 323, the wire 332, and theelectrodes 331 are further positioned outside the large-diameter lenscarrier 321, resulting in an increased size of the imaging apparatus 300itself.

To address the problem, the imaging apparatus in the third embodiment towhich the invention is applied has the configuration shown in FIGS. 8Aand 8B to achieve size reduction. FIG. 8A is a top view of an imagingapparatus 350, and FIG. 8B is a side view (cross-sectional view) of theimaging apparatus 350.

The imaging apparatus 350 shown in FIGS. 8A and 8B has a configurationthat is basically the same as that of the imaging apparatus 300 ofrelated art shown in FIGS. 7A and 7B. The imaging apparatus 350 includesa housing 351, a lens barrel 352, and an imaging device 353. Lenses 21,22, and 23 are assembled into the lens barrel 352 and held therein. Athread 361 is provided on the outer side surface of the lens barrel 352.

A lens carrier 371 is provided in the housing 351. A thread 372 isprovided on the inner side (inner diameter) of the lens carrier 371.Hooks 373-1 and 373-2 are provided in predetermined positions on theouter (outer shape) side surface of the lens carrier 371. The hooks373-1 and 373-2 are disposed on opposite sides of the lens carrier 371.A wire 382 made of a shape memory alloy is hooked to the hooks 373-1 and373-2.

The wire 382 is also connected to electrodes 381-1 and 381-2. When acurrent is conducted from the electrodes 381-1 and 381-2 through thewire 382 and the temperature thereof increases, the wire 382 made of ashape memory alloy decreases in length. When the length of the wire 382decreases, the hooks 373 to which the wire 382 is hooked are liftedrelative to the housing 351.

Since the hooks 373 are integrated with the lens carrier 371, the hooks373 lifted relative to the housing 351 lift the lens carrier 371relative to the housing 351. In this way, the lens carrier 371 isdriven. Conversely, when the current flowing through the wire 382 isterminated, the temperature thereof decreases and the length thereofincreases. When the length of the wire 382 increases (returns back toits original length), the hooks 373 and hence the lens carrier 371 arelowered.

The lens barrel 352, which holds the lenses, fits into the lens carrier371. Driving the lens carrier 371 in the way described above thereforechanges the position of the lenses held in the lens barrel 352 and hencethe focal distance is adjusted. That is, autofocusing is performed.

The structure of the lens barrel 352 will further be described.Referring to FIG. 8B, the lens barrel 352 has a stepped shape, a shapehaving two stepped sections in the configuration shown in FIG. 8B. Astepped section 391 contains the lens 23, and a stepped section 392contains the lenses 21 and 22. As shown in FIG. 8B, the sizes of thelenses 21 to 23 satisfy the following relationship.lens 21<lens 22<lens 23

The diameter of the stepped section 391 containing the lens 23 istherefore larger than that of the stepped section 392 containing thelenses 21 and 22. The diameter of the stepped section 391 is slightlylarger than that of the lens 23. The diameter of the stepped section 392is slightly larger than that of the lens 22 but smaller than that of thelens 23.

The thread 361 is provided on the stepped section 392. The thread 361provided on the stepped section 392 engages the thread 372 provided onthe lens carrier 371. The diameter of the lens carrier 371 is sized insuch a way that the thread 361 engages the thread 372. The diameter ofthe lens carrier 371 is therefore sized to be slightly larger than thatof the stepped section 392.

Further, the height of the stepped section 392 is shorter than theheight of the lens carrier 371. The height used herein means the lengthin the up-down direction in FIG. 8B (the direction toward or away fromthe imaging device 353). The height of the lens carrier 371 isdetermined in such a way that the stepped section 391 of the lens barrel352 does not come into contact with an end of the lens carrier 371 whenthe lens barrel 352 is fixed to the lens carrier 371.

The length of the hooks 373 attached to the lens carrier 371 is sized insuch a way that part of the tips of the hooks 373 extends off thelargest diameter (largest outer diameter) of the lens barrel 352 or thetips are preferably within the diameter of the lens barrel 352.

The imaging apparatus 300 (FIGS. 7A and 7B) of related art is nowcompared with the imaging apparatus 350 (FIGS. 8A and 8B) in the thirdembodiment. Each of the imaging apparatus 300 and the imaging apparatus350 includes the lenses 21 to 23. The imaging apparatus 300 and theimaging apparatus 350 therefore do not differ from each other in termsof optical system and can hence capture images having the same imagequality. Further, the imaging device 303 in the imaging apparatus 300and the imaging device 353 in the imaging apparatus 350 have the samesize or the same number of pixels and can capture images having the sameimage quality in this regard as well.

It is, however, obvious that the imaging apparatus 350 is smaller thanthe imaging apparatus 300. The reason for this is that the lens barrel352 in the imaging apparatus 350 has a stepped shape and the diameter ofthe stepped section 392 accommodating the smaller lenses is smaller thanthe diameter of the stepped section 391 accommodating the larger lens.The size of the imaging apparatus 350 can be reduced accordingly. Thesize of the imaging apparatus 350 is reduced because the space createdby the difference between the stepped sections 391 and 392,specifically, the difference in diameter between the stepped sections391 and 392, accommodates all or part of the lens carrier 371, the hooks373, and the electrodes 381.

That is, the size of the imaging apparatus 350 can be reduced by shapingthe lens barrel 352 in such a way that the diameter thereof graduallydecreases in correspondence with the sizes of the lenses to beaccommodated, providing the thread 361 on the stepped section having thesmaller diameter so that the threaded portion engages the lens carrier371, and assembling a driver including the hooks 373, the electrodes381, and the wire 382 on the side where the diameter is smaller.

In the above description of “shaping the lens barrel 352 in such a waythat the diameter thereof gradually decreases in correspondence with thesizes of the lenses to be accommodated,” “the diameter thereof graduallydecreases” means that the following shapes can be employed. That is, forexample, a stepped shape, like the stepped sections 391 and 392 shown inFIG. 8B, can be employed. Although not shown, when three lenses, such asthe lenses 21 to 23 shown in FIG. 8B, are incorporated, a stepped shapenot formed of two stepped sections but formed of three stepped sectionscorresponding to the number of lenses can be employed.

Alternatively, although not shown, instead of a stepped shape, forexample, a cone shape (part of a cone shape) whose diameter graduallyand continuously decreases in the direction away from the imaging device353 can be employed. Still alternatively, for example, a combined shapein which the threaded portion (corresponding to the stepped section 392in FIG. 8B) has a cylindrical shape and the non-threaded portion(corresponding to the stepped section 391 in FIG. 8B) has part of a coneshape can be employed. Still alternatively, any shape one can think offrom the shapes described above can be employed.

The imaging apparatus 300 of related art shown in FIGS. 7A and 7Bdisadvantageously has a structure that causes an increase in size of theimaging apparatus 300 itself, as described above. However, since theimaging apparatus 350 shown in FIGS. 8A and 8B, to which the thirdembodiment of the invention is applied, has the configuration describedabove, the lens carrier 371 is positioned outside the lens barrel 352but inside the largest-diameter (outer diameter) portion of the lensbarrel 352.

Further, all or part of the driver including the hooks 373, theelectrodes 381, and the wire 382 positioned outside the lens carrier 371is positioned inside the largest-diameter portion of the lens barrel352. Since none or only part of the lens carrier 371, the hooks 373, theelectrodes 381, and the wire 382 is thus positioned outside the largestdiameter of the lens barrel 352, the size of the imaging apparatus 350itself is reduced.

In other words, the diameter of the lens barrel 352 on the side wherethe imaging device 353 is present is large, whereas the diameter of thelens barrel 352 on the opposite side is small. Since the diameters ofthe two portions of the lens barrel 352 differ from each other, a spaceis created where the difference is present. Accommodating drive means(the hooks 373, the electrodes 381, and the wire 382 in this case) forvertically moving the lens carrier 371 relative to the imaging plane ofthe imaging device 353 in the space allows the size of the imagingapparatus 350 to be reduced.

As described above, the size of the imaging apparatus can be reduced byapplying the invention. Further, the size reduction will not degrade thequality of a captured image.

The focus adjustment carried out at the time of manufacture by using theengagement between the lens barrel 352 and the lens carrier 371 can becarried out in the same manner as the imaging apparatus 300 of relatedart.

The imaging apparatus 350 shown in FIGS. 8A and 8B includes the twohooks 373, the two electrodes 381, and the wire 382 connected to thehooks 373 and the electrodes 381 and surrounding the lens carrier 371.The imaging apparatus 350 may alternatively include one of the hooks373, the two electrodes 381, and the wire 382 connected to the hook 373and the electrodes 381 and surrounding the lens carrier 371. That is,the imaging apparatus 350 can, for example, be configured in such a waythat the ends of the wire 382 are connected to the electrodes 381-1 and381-2 and the hook 373-1 (or hook 373-2) is positioned in a centralportion of the wire 382.

The configuration described above does not increase the size of theconfiguration of the imaging apparatus 350, but the imaging apparatus350 can still be reduced in size.

The above first to third embodiments have been described with referenceto a case where the lens closer to the imaging device is larger and thesize of the lenses decreases in the direction away from the imagingdevice. The invention is, however, not limited to the lens layoutdescribed above. That is, for example, the invention can be applied to acase where the lens farther away from the imaging device is larger andthe size of the lenses decreases in the direction toward the imagingdevice.

When the lens layout described above is employed, the threads and thedriver are provided on the side where the stepped portion accommodatingsmaller lenses is present. The size of the imaging apparatus can, ofcourse, be reduced even when the lens layout described above isemployed, as in the above embodiments.

The above embodiments have been described with reference to the imagingapparatus including the three lenses 21 to 23, but the invention is notnecessarily applied to an imaging apparatus including three lenses. Thatis, the invention can be applied to an imaging apparatus including aplurality of lenses 21 to 24, as shown in FIG. 9.

When a plurality of lenses, such as lenses 21 to 23 shown in FIG. 3 orlenses 21 to 24 shown in FIG. 9, are provided and the diameter of thelenses increases (or decreases) toward the imaging device, the lensbarrel holding the plurality of lenses is configured not to simply havea cylindrical shape but have a stepped shape according to the diametersof the lenses or a shape at least part of which gradually decreases indiameter. Shaping the lens carrier that holds the lens barrel inaccordance with the shape of the lens barrel provides a sufficient spacebetween the lens carrier and the inner wall of the lens module on theside where a subject is present, whereby the actuator can be disposed inthe space. The lens module can therefore be reduced in size.

In an imaging apparatus of related art having a structure in which nothread is provided on the lens barrel and the lens carrier, the focusadjustment with respect to the imaging device may not be carried out. Inthe present invention, threads are provided on the lens barrel and thelens carrier. Providing threads on the lens barrel and the lens carrierallows the focus adjustment with respect to the imaging device to becarried out, for example, at the time of manufacture.

The stroke typically required to perform autofocusing can be minimizedand the requirements on actuator characteristics can be lowered byapplying the invention. Further, the resultant smaller stroke or movablerange advantageously reduces power consumption.

Embodiments of the invention are not limited to those described above,but a variety of changes can be made to the extent that they do notdepart from the spirit of the invention.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-163284 filedin the Japan Patent Office on Jul. 10, 2009, the entire contents ofwhich is hereby incorporated by reference.

What is claimed:
 1. An imaging apparatus comprising: a plurality oflenses including a first lens, a second lens, and a third lens arrangedin this order from a light incident side, wherein a diameter of thefirst lens is smaller than a diameter of the second lens and thediameter of the second lens is smaller than a diameter of the thirdlens; a first member configured to hold the plurality of lenses, thefirst member including a first portion and a second portion, wherein thefirst portion has a first outer diameter and the second portion has asecond outer diameter that is smaller than the first outer diameter; asecond member engaged with the second portion of the first member; animaging device configured to receive an incident light through theplurality of lenses; a driving member configured to drive the firstmember in a vertical direction relative to the imaging device, thedriving member including a coil disposed on the second member and amagnet disposed opposite to the coil; and a housing configured tosurround the first member, the second member, and the driving member,wherein a virtual line between an inner surface of the housing at apoint opposite to the driving device in a horizontal direction, and anouter surface of the imaging device lies in a virtual plane extending inthe vertical direction.
 2. The imaging apparatus according to claim 1,wherein the first portion has a first inner diameter and the secondportion has a second inner diameter that is smaller than the first innerdiameter.
 3. The imaging apparatus according to claim 1, wherein thefirst portion is configured to engage the third lens.
 4. The imagingapparatus according to claim 1, wherein the second portion and the firstportion are arranged in this order from the light incident side.
 5. Theimaging apparatus according to claim 1, wherein an outer surface of thefirst member includes a first thread; an inner surface of the secondmember includes a second thread; and the first thread and the secondthread are engaged to one another.
 6. The imaging apparatus according toclaim 1, wherein an inner diameter of the second member is smaller thanthe first outer diameter of the first member.
 7. The imaging apparatusaccording to claim 1, wherein the first lens, the second lens, and thethird lens are fixed relative to one another and movable relative to theimaging device.
 8. The imaging apparatus according to claim 1, whereinan inner surface of the first member has a stepped shape.
 9. The imagingapparatus according to claim 1, wherein the first member has a shapeincluding a cylindrical portion and a conical portion.
 10. The imagingapparatus according to claim 1, further comprising a fourth lensarranged between the third lens and the imaging device, wherein thediameter of the third lens is smaller than a diameter of the fourthlens.
 11. A mobile phone, comprising: an imaging apparatus including: aplurality of lenses including a first lens, a second lens, and a thirdlens arranged in this order from a light incident side, wherein adiameter of the first lens is smaller than a diameter of the second lensand the diameter of the second lens is smaller than a diameter of thethird lens, a first member configured to hold the plurality of lenses,the first member including a first portion and a second portion, whereinthe first portion has a first outer diameter and the second portion hasa second outer diameter that is smaller than the first outer diameter, asecond member engaged with the second portion of the first member, animaging device configured to receive an incident light through theplurality of lenses, a driving member configured to drive the firstmember in a vertical direction relative to the imaging device, thedriving member including a coil disposed on the second member and amagnet disposed opposite to the coil, and a housing configured tosurround the first member, the second member, and the driving member,wherein a virtual line between an inner surface of the housing at apoint opposite to the driving device in a horizontal direction, and anouter surface of the imaging device lies in a virtual plane extending inthe vertical direction.
 12. The mobile phone according to claim 11,wherein the first portion has a first inner diameter and the secondportion has a second inner diameter that is smaller than the first innerdiameter.
 13. The mobile phone according to claim 11, wherein the firstportion is configured to engage the third lens.
 14. The mobile phoneaccording to claim 11, wherein the second portion and the first portionare arranged in this order from the light incident side.
 15. The mobilephone according to claim 11, wherein an outer surface of the firstmember includes a first thread; an inner surface of the second memberincludes a second thread; and the first thread and the second thread areengaged to one another.
 16. The mobile phone according to claim 11,wherein an inner diameter of the second member is smaller than the firstouter diameter of the first member.
 17. The mobile phone according toclaim 11, wherein the first lens, the second lens, and the third lensare fixed relative to one another and movable relative to the imagingdevice.
 18. The mobile phone according to claim 11, wherein an innersurface of the first member has a stepped shape.
 19. The mobile phoneaccording to claim 11, wherein the first member has a shape including acylindrical portion and a conical portion.
 20. The mobile phoneaccording to claim 11, further comprising a fourth lens arranged betweenthe third lens and the imaging device, wherein the diameter of the thirdlens is smaller than a diameter of the fourth lens.